docs(README): add tree with dynamic template example

Author: thgreasi

README.md

@@ -40,7 +40,7 @@ Apply the directive to your form elements:
 * `ui-sortable` element should only contain one `ng-repeat` and not any other elements (above or below).  
   Otherwise the index matching of the generated DOM elements and the `ng-model`'s items will break.  
   **In other words: The items of `ng-model` must match the indexes of the generated DOM elements.**
-* `ui-sortable` lists containing many 'types' of items can be implemented by using dynamic template loading [with ng-include](http://stackoverflow.com/questions/14607879/angularjs-load-dynamic-template-html-within-directive/14621927#14621927) or a [loader directive](https://gist.github.com/thgreasi/7152499c0e91973c4820), to determine how each model item should be rendered.
+* `ui-sortable` lists containing many 'types' of items can be implemented by using dynamic template loading [with ng-include](http://stackoverflow.com/questions/14607879/angularjs-load-dynamic-template-html-within-directive/14621927#14621927) or a [loader directive](https://gist.github.com/thgreasi/7152499c0e91973c4820), to determine how each model item should be rendered. Also take a look at the [Tree with dynamic template](http://codepen.io/thgreasi/pen/uyHFC) example.
 
 ### Options
 
@@ -136,6 +136,7 @@ For more details about the events check the [jQueryUI API documentation](http://
 - [Filtering](http://codepen.io/thgreasi/pen/mzGbq) ([details](https://github.com/angular-ui/ui-sortable/issues/113))
 - [Ordering 1](http://codepen.io/thgreasi/pen/iKEHd) & [Ordering 2](http://plnkr.co/edit/XPUzJjdvwE0QWQ6py6mQ?p=preview) ([details](https://github.com/angular-ui/ui-sortable/issues/70))
 - [Cloning](http://codepen.io/thgreasi/pen/qmvhG) ([details](https://github.com/angular-ui/ui-sortable/issues/139))
+- [Tree with dynamic template](http://codepen.io/thgreasi/pen/uyHFC)
 
 ## Reporting Issues